584 THE POPULAR SCIENCE MONTHLY. 



connection with each other. Not only does the philosophy of chem- 

 istry rest upon i:)hysical conceptions ; but, moreover, chemical methods 

 involve physical jDrinciples. There is, however, a distinction to be 

 made ; for, while some of the departments of physics are best studied 

 as a preparation for chemistry, there are other subjects which are best 

 deferred until the student has some knowledge of chemical facts. 

 Among the preliminary subjects we should mention elementary me- 

 chanics, including hydrostatics and pneumatics, and also thermotics ; 

 while electricity, acoustics, and optics, including the large subject of 

 radiant energy, may well be deferred until after the study of chemistry. 



In the study both of chemistry and physics there are of course two 

 definite objects to be kept in view : In the first place, a knowledge 

 of the facts of the science is to be acquired ; in the second place, the 

 student must learn by experience how these facts have been discovered. 

 It would bo obvious, from a moment's reflection, that a knowledge of 

 the circumstances under which the facts of Nature are revealed to the 

 student is essential to a complete apprehension of the facts themselves. 

 The child who is taught that the earth moves in an elliptical orbit 

 around the sun in one year does not in the least grasp the wonderful 

 fact thus stated, and will not come to realize it until he connects the 

 statement with the nightly precession of the stars in the heavens. And 

 it is just such a connection as this which the teacher must seek to 

 establish in all scientific teaching. In experimental science such a 

 connection is most readily established in the mind of the student by 

 means of a series of well-arranged experiments, which each one repeats 

 for himself at the laboratory table. Obviously, however, it is impos- 

 sible, in a limited course of teaching, to go over the whole ground of 

 chemistry or physics in this way, or even over that small portion of 

 the ground with which the average scientific student can expect to 

 become acquainted. Nor is this necessary ; for, after one has realized 

 the connection between phenomena and conclusion in a number of 

 instances, the mind will fully comprehend that a similar connection 

 exists in other cases, and will understand the limitations with which 

 scientific conclusions are to be received. 



Hence, it seems to me that, in teaching chemistry or physics, it is 

 best to combine a course of lectures which should give a broad view 

 of the whole ground with a course of laboratory instruction, which 

 must necessarily be more or less restricted. Experimental lectures 

 are, I am convinced, much the best way of presenting these subjects 

 as systematic portions of knowledge. It is not necessary that the 

 lectures should be formal, but it is all-important that they should be 

 given in such a way that the interest of the student should be awakened, 

 and that they should be fully illustrated by specimens and experiments. 

 What we read in a book does not make one half the impression that 

 is jiroduced by the words of a living teacher, nor can we realize the 

 facts unless we see the phenomena described. There is undoubtedly, 



